Digital Electronics: Principles, Devices and Applications

250 Digital ElectronicsExample 7.1For the half-adder circuit of Fig. 7.23(a), the inputs applied at A and B are as shown in Fig. 7.23(b).Plot the corresponding SUM and CARRY outputs on the same scale.SolutionThe SUM and CARRY waveforms can be plotted from our knowledge of the truth table of the halfadder.All that we need to remember to solve this problem is that 0 +0 yields a ‘0’ as the SUM outputand a ‘0’ as the CARRY. 0 + 1or1+ 0 yield ‘1’ as the SUM output and ‘0’ as the CARRY. 1 + 1produces a ‘0’ as the SUM output and a ‘1’ as the CARRY. The output waveforms are as shown inFig. 7.24.ABHalf AdderSC(a)AB(b)Figure 7.23 Example 7.1.Sum-outputCarry-outputFigure 7.24 Solution to example 7.1.